Electronic components can be mounted on a ceramic substrate and electrically connected to each other through metallized conductors carried by the substrate. Lee U.S. Pat. No. 4,292,647 discloses a semiconductor package including a plurality of electronic chips mounted on a ceramic substrate and provided with individual heat conductive elements mounted directly above them. Moore U.S. Pat. No. 4,541,004 discloses placing heat conducting pins either in a semiconductor package or in a substrate attached to a semiconductor package.